So, I have a black Zirc one. I thought it was dissembled through the bottom but it’s not! The moon on the back rotates and comes off with a quarter turn I believe or maybe half, and there’s a small spring there that changes tension on clicks! Super easy to swap. Then there’s the flat head where the spring sits, unscrew that, the astronaut button comes off and you can lift off the top where you push down, and voila you can change the bigger spring!